1. Department of Biology and Wildlife Diseases, Faculty of Veterinary Hygiene and Ecology, University of Veterinary Sciences Brno, Palackého tř. 1946/1, 61242 Brno, CZECH REPUBLIC
2. Technisches Büro für Biologie Mag. Dr. Rainer Raab, Quadenstrasse 13, 2232 Deutsch-Wagram, AUSTRIA
3. Austrian Ornithological Centre/Fieldstation Seebarn, Konrad Lorenz Institute of Ethology, University of Veterinary Medicine, Vienna, Savoyenstraße 1a, 1160 Vienna, AUSTRIA